Preparation of an octenone



Patented May 12, 1953 PREPARATION OF AN OCTENONE Walter Kimel, HighlandPark, N. J., assignor to Hofi'mann-La Roche Inc., Nutley, N. J., acorporation of New Jersey No Drawing. Origina Serial No. 230,075.

tion February 14, 1952,

2 Claims.

This invention relates to a novel chemical compound, and to processes ofpreparing and converting said compound. More particularly, the inventionis concerned with the new substance t-vinylisopropyl acetoacetate, whichcan also be designated 1,1-dimethyl-propen-2-yl 3- oxobutanoate, andwhich can be represented by the formula CH3COCH2COOC(CH3)2CH=CH2. Thissubstance can be prepared by condensing 2- methyl-buten-3-o1-2 withdiketene, and the product can be converted by heating (with loss ofcarbon dioxide) into 2-methyl-hepten-2-one-6. The latter can beconverted to citral, geraniol or pseudoionone by known processes, andthus the invention is of interest to the pharmaceutical, perfume andsoap industries.

The invention is further disclosed in the following example, which isillustrative but not limitative thereof.

Example In a flask equipped with a stirrer, a thermometer, a droppingfunnel and a drying tube, 0.3 g. of sodium was reacted with 86 g. (1.0mol) of 2-methyl-buten-3-ol-2. The solution was cooled to C. and 101 g.(1.2 mols) of diketene was added slowly, with efiicient stirring, duringone hour, Whilemaintaining the temperature at 0 C. The mixture was thenallowed to stand for 24 hours at 0 C.

The resulting dark orange solution was diluted with 200 cc. of ether andextracted three times with 150 cc. portions of saturated sodiumbicarbonate solution, and then Washed with water un- 1 application June5, 1951, Divided and this applica- Serial No. 271,644

2 til neutral. The organic solution was dried over calcium sulphate, andconcentrated in vacuo. The residue was fractionated under reducedpressure to yield t-vinylisopropyl acetoacetate, B. P. (8 mm.) 84-86 C.;n =l.4364.

39.0 g. (0.229 mol) of t-vinylisopropyl acetoacetate was placed in aflask equipped with a reflux condenser, a thermometer, and a finecapillary tube for the introduction of nitrogen. A slow stream ofnitrogen was introduced and the ester was heated at a very gentle refluxfor about 1 /3 hours at which time the evolution of carbon dioxide hadceased. The residue in the flask was fractionated under reduced pressureto yield 2- methyl-hepten-2-one-6, B. P. mm.) 83-85 0.; n =1.4369. Thelatter product was further identified by conversion to itssemicarbazone, M. P. 134.5-135.5 C., and by conversion to its2,4:-dinitrophenylhydrazone, M. P. 86.3 C.

This application is a division of my copending application Serial No.230,075, filed June 5, 1951.

Iclaim:

1 A process which comprises condensing diketene with2-methyl-buten-3-ol-2 and decarboxylating the condensation product toproduce 2-methyl-hepten-2-one-6.

2. A process of preparing 2-methyl-hepten-2- one-6 which comprisesheating t-vinylisopropyl acetoacetate to eliminate carbon dioxidetherefrom.

WALTER KIMEL.

No references cited.

2. A PROCESS OF PREPARING 2-METHYL-HEPTEN-2ONE-6 WHICH COMPRISES HEATINGT-VINYLISOPROPYL ACETOACETATE TO ELIMINATE CARBON DIOXIDE THEREFROM.